The operation of internal combustion engines is well known to those of skill in the art. For example, a typical one-cylinder, two-valve internal combustion engine includes a reciprocating piston which defines a combustion chamber for the combustion of a fuel charge comprising a fuel-air mixture, with the combustion chamber being the variable volume between the top of the piston and the cylinder head. The cylinder head contains an intake poppet valve (“intake valve”), an exhaust poppet valve (“exhaust valve”), and an ignition source such as a spark plug. The piston is connected via a connecting rod to a crankshaft which converts the reciprocating linear motion of the piston into a useful torque on the crankshaft.
During the intake stroke, the piston moves downward and away from the cylinder head, lowering the pressure in the combustion chamber relative to the pressure on the other side of the intake valve. As the piston travels downward, the intake valve extends into the combustion chamber, or “lifts,” wherein the pressure differential between the combustion chamber and the intake port causes the fuel charge to flow into the combustion chamber. The intake valve then closes and the fuel mixture is compressed in the combustion chamber as the piston travels toward the cylinder head. At top dead center, the piston is at its maximum vertical position and the fuel charge is at its maximum compression. The fuel mixture is then ignited, driving the piston downwards and generating a torque on the crank shaft. The exhaust valve then opens and the positive pressure of the exhaust gas causes it to flow out of the combustion chamber and into the exhaust port.
As understood by one of skill in the art, the amount of fuel charge that can flow into the combustion chamber during the limited time that the intake valve is open is a function of the “intake valve area,” which consists of the two-dimensional area between the intake valve at maximum lift and the cylinder head. Since an internal combustion engine is essentially an air pump, the power and efficiency of an internal combustion engine is directly proportional to the intake valve area. Similarly, the power and efficiency of an internal combustion engine is also proportional to the amount of exhaust gas that can be expelled from the combustion chamber during the limited time that the exhaust valve is open. The amount of exhaust gas expelled is a function of the exhaust valve area. Similarly, the power and efficiency of an internal combustion engine is also a function of how well the fuel and air have been mixed just prior to combustion.
Poppet valves as known in the art generally comprise a narrow valve stem which rapidly widens at one end into a circular valve head. The valve head fits into a corresponding circular opening in the cylinder head such that the combustion chamber is a closed volume when the intake and exhaust valves are closed. Modern internal combustion engines sometimes use more than two total valves to increase the total intake and exhaust valve areas, providing greater engine efficiency and power output. For example, some internal combustion engines use two intake valves and two exhaust valves, which provide a larger total valve area than a two-valve design. Some engines even use three intake valves and two exhaust valves to further increase total valve area. However, there is a limit to the number of valves that can be used in a given cylinder head because the area of the cylinder head in which the valves rest is finite. Additionally, using a very large number of small valves does not improve engine efficiency because a very small valve area has a greater flow resistance per unit area than a larger valve area.
Internal combustion engines use fuels that are derived from crude oil, the supply of which is increasingly finite and unstable. When combustion engines burn such fuels they produce emissions that cause a negative impact on the environment—and governments have promulgated and enforced increasingly stringent environmental regulations as a result. But alternatives to the internal combustion engine are few, and they are costly. In light of these and other developments, there is an increasing need in the art to extract more power and efficiency from combustion engines.
A poppet valve that offered an increased valve area would produce more power per unit of fuel than existing poppet valves, thus enabling manufacturers to produce engines that consume less fuel without sacrificing power. The same results would inhere from the use of a poppet valve that caused the fuel charge to mix more thoroughly in the combustion chamber, such as by creating a vortex in the combustion chamber. Moreover, a poppet valve combining these elements would increase fuel efficiency more than would a poppet valve offering either element standing alone. A combustion engine using poppet valves that offered an increased valve area or caused the fuel charge to mix more thoroughly, or both, would, by increasing fuel efficiency, enable users of combustion systems to reduce their energy consumption. This, in turn, would materially contribute to the more efficient utilization and conservation of energy resources. The reduction in energy consumption also would lead to a reduction in harmful emissions, thus materially enhancing the quality of the environment.